This invention concerns open-end spinning in general, and in particular a device therefor having two friction rollers operatively associated with one another to form a spinning nip. Such rollers are driven in the same direction during spinning operation. At least one of the rollers is embodied as a suction roller with a perforated casing, over-mounted at one end. A suction insert, received in the suction roller, has a suction slit and is connected to a negative pressure (i.e. vacuum) source.
Friction rollers embodied as suction rollers and equipped with drive shafts which are over-mounted on rolling bearings are known in the art (e.g. German Pat. DE-OS No. 2,810,184). In such a device, a connecting branch of the suction insert, which is received within the casing of the friction rollers, is located on the face of the casing which opposes drive shafts therefor. Thus, feeding through the fiber feeding channel and suction through the suction insert tend to be in the same direction. Bearings for such an arrangement are often complicated, and even so are not sufficiently stable to properly maintain the uniformly narrow distance between the friction rollers which is required for spinning.
One solution proposed to eliminate these disadvantages was to make the suction insert in the form of a shaft, on which are located rolling bearings for the sleeve extending beyond the area of the suction slit (e.g. German Pat. No. DE-OS No. 3,316,658). However, such an arrangement requires that the distance between the perforated sleeve and the suction insert be widened by the width of the bearing headroom. Such distance must then be bridged in turn by an appropriate tubular connecting piece. Increased manufacturing efforts and a friction roller with a greater diameter are required for such an approach, and hence inevitably lead to higher costs. Furthermore, air-flow conditions are adversely affected, which in turn has an adverse effect on spinning conditions.